Justification of Red List Category
This species is estimated to be undergoing a moderately rapid population decline. Therefore, it is considered to be Near Threatened.
Rosenberg et al. (2016) estimate the population size to be 1,800,000 mature individuals.
Rosenberg et al. (2016) gives two different values for the population reduction between 1970 and 2014: 69% and 67%. Assuming declines have been at a similar rate across this time period, this would equate to a decline of 36.1% or 34.5% over three generations (16.8 years) respectively. Christmas Bird Count data from 1966-2017 also shows an annual decline of 2.15% (1.20-3.21%), equating to a reduction of 30.58% (18.33-42.18%) over three generations (T. Meehan in litt. 2018), while Canadian Breeding Bird Survey data suggests an annual 3% decline (Mills 2018). However, data from Sauer et al. (2017) suggest that rates of decline may have slowed over recent years. An extrapolated trend between 2001 and 2015 to 2018 gives an estimated annual decrease of 1.67% (0.15 to 2.91%) (Sauer et al. 2017). This would equate to a reduction of 24.6% (2.5-39.1%) over three generations, assuming exponential decline. However, 2005-2015 trends from Sauer et al. (2017) show a non-significant decline of 1.29% per year (between 2.94% decline to 0.71% increase), which would roughly equate to a 19.6% decrease (39.4% decrease to 12.6% increase) over three generations. Given there is some slight uncertainty, and threats are likely to continue into the future the rate of decline has been tentatively placed here in the range 20-29% over three generations.
Antrostomus vociferus is a migratory species, breeding from southern central to eastern Canada and through central to eastern U.S.A.. The species overwinters in south-eastern U.S.A., Mexico and into Central America.
During the breeding season the species is predominantly found in forested habitats, preferring dry deciduous or mixed forests, with little or no underbrush (Cink et al. 2017). However, it will also occur in semi-open habitats too, such as road corridors and rural farmland (Cink et al. 2017). There is little information about habitat preferences during migration and in the non-breeding range, but in south-eastern U.S.A. it is mainly found in mixed woodland (Cink et al. 2017). It feeds during moonlit times of the night as well as at dawn and dusk, usually sallying after insect prey (Cink et al. 2017). It nests directly in the leaf litter, not building a nest, and two clutches may be attempted; with the first being in April-early June and the second brood being attempted c.30-35 days after the first (see Cink et al. 2017).
The species may be able to tolerate some habitat degradation, but the main threats to the species appear to be forest loss and degradation. Clearance of woodland for agriculture and the closing up of forest gaps due as a result of tree succession appear to lead to local declines (see Cink et al. 2017). Grazing of forest underbrush (used as nesting cover by the species) by sheep may also have led to its disappearance in some areas (see Cink et al. 2017). Habitat loss (and by-product increases in predation) due to urbanisation may have led to the species's disappearance from south-east Pennsylvania (see Cink et al. 2017). The species also sits at the side of roads, which means it is at high risk from traffic collision, and there are untested theories that industrial pollution and pesticide use could be reducing prey abundance (see Cink et al. 2017).
Conservation Actions Underway
This species is listed as a Threatened species in Kansas (Platt 1974), and is placed on the Yellow watch list by Partners in Flight (Rosenberg et al. 2016).
Conservation Actions Proposed
Conduct research to better understand the threats to this species. Plan appropriate measures to aid species recovery.
Text account compilers
Symes, A., Westrip, J.
Meehan, T., Artuso, C.
BirdLife International (2021) Species factsheet: Antrostomus vociferus. Downloaded from http://www.birdlife.org on 24/10/2021. Recommended citation for factsheets for more than one species: BirdLife International (2021) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 24/10/2021.